Pass Parameter to Base Class Constructor while creating Derived class Object
Consider two classes A and B
class A
{
public:
A(int);
~A();
};
class B : public A
{
public:
B(int);
~B();
};
int main()
{
A* aobj;
B* bobj = new bobj(5);
}
Now the class B inherits A.
I want to create an object of B. I am aware that creating a derived class object, will also invoke the base class constructor , but that is the default constructor without any parameters.
What i want is that B to take a parameter (say 5), and pass it on to the constructor of A.
Please show some code to demonstrate this concept.
c++ oop constructor
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
add a comment |
Consider two classes A and B
class A
{
public:
A(int);
~A();
};
class B : public A
{
public:
B(int);
~B();
};
int main()
{
A* aobj;
B* bobj = new bobj(5);
}
Now the class B inherits A.
I want to create an object of B. I am aware that creating a derived class object, will also invoke the base class constructor , but that is the default constructor without any parameters.
What i want is that B to take a parameter (say 5), and pass it on to the constructor of A.
Please show some code to demonstrate this concept.
c++ oop constructor
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
2
B::B(int val) : A(val) {}
– Andrew
May 16 '13 at 11:11
2
I thought you want to make the destructor take arguments, didn't look like a typo to me. And no need from!!. Down-vote reverted, remark deleted.
– Kiril Kirov
May 16 '13 at 11:21
add a comment |
Consider two classes A and B
class A
{
public:
A(int);
~A();
};
class B : public A
{
public:
B(int);
~B();
};
int main()
{
A* aobj;
B* bobj = new bobj(5);
}
Now the class B inherits A.
I want to create an object of B. I am aware that creating a derived class object, will also invoke the base class constructor , but that is the default constructor without any parameters.
What i want is that B to take a parameter (say 5), and pass it on to the constructor of A.
Please show some code to demonstrate this concept.
c++ oop constructor
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
Consider two classes A and B
class A
{
public:
A(int);
~A();
};
class B : public A
{
public:
B(int);
~B();
};
int main()
{
A* aobj;
B* bobj = new bobj(5);
}
Now the class B inherits A.
I want to create an object of B. I am aware that creating a derived class object, will also invoke the base class constructor , but that is the default constructor without any parameters.
What i want is that B to take a parameter (say 5), and pass it on to the constructor of A.
Please show some code to demonstrate this concept.
c++ oop constructor
c++ oop constructor
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
edited May 16 '13 at 15:15
Barath Ravikumar
4,30311336
4,30311336
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
asked May 16 '13 at 11:09
CodeCrusaderCodeCrusader
1942212
1942212
2
B::B(int val) : A(val) {}
– Andrew
May 16 '13 at 11:11
2
I thought you want to make the destructor take arguments, didn't look like a typo to me. And no need from!!. Down-vote reverted, remark deleted.
– Kiril Kirov
May 16 '13 at 11:21
add a comment |
2
B::B(int val) : A(val) {}
– Andrew
May 16 '13 at 11:11
2
I thought you want to make the destructor take arguments, didn't look like a typo to me. And no need from!!. Down-vote reverted, remark deleted.
– Kiril Kirov
May 16 '13 at 11:21
2
2
B::B(int val) : A(val) {}
– Andrew
May 16 '13 at 11:11
B::B(int val) : A(val) {}
– Andrew
May 16 '13 at 11:11
2
2
I thought you want to make the destructor take arguments, didn't look like a typo to me. And no need from
!!. Down-vote reverted, remark deleted.– Kiril Kirov
May 16 '13 at 11:21
I thought you want to make the destructor take arguments, didn't look like a typo to me. And no need from
!!. Down-vote reverted, remark deleted.– Kiril Kirov
May 16 '13 at 11:21
add a comment |
4 Answers
4
active
oldest
votes
Use base member initialisation:
class B : public A
{
public:
B(int a) : A(a)
{
}
~B();
};
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
add a comment |
B::B(int x):A(x)
{
//Body of B constructor
}
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
add a comment |
If you are using your derived class constructor just to pass arguments to base class then you can also do it in a shorter way in C++11:
class B : public A
{
using A::A;
};
Note that I have not even used "public" access specifier before it. This is not required since inherited constructors are implicitly declared with same access level as in the base class.
For more details, please refer to section Inheriting constructors at: https://en.cppreference.com/w/cpp/language/using_declaration
Also you may refer to https://softwareengineering.stackexchange.com/a/307648 to understand limitations on constructor inheritance.
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
add a comment |
class A
{ public:
int aval;
A(int a):aval(a){};
~A();
};
class B : public A
{ public:
int bval;
B(int a,int b):bval(a),A(b){};
~B();
};
int main()
{
B *bobj = new bobj(5,6);
//or
A *aobj=new bobj(5,6);
}
In this case you are assigning the values for base class and derived class .
answered Nov 20 '18 at 11:58
WilsonWilson
112
add a comment |
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
Use base member initialisation:
class B : public A
{
public:
B(int a) : A(a)
{
}
~B();
};
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
add a comment |
Use base member initialisation:
class B : public A
{
public:
B(int a) : A(a)
{
}
~B();
};
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
add a comment |
Use base member initialisation:
class B : public A
{
public:
B(int a) : A(a)
{
}
~B();
};
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
Use base member initialisation:
class B : public A
{
public:
B(int a) : A(a)
{
}
~B();
};
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
edited Feb 14 '14 at 8:54
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
answered May 16 '13 at 11:14
BathshebaBathsheba
179k27254381
179k27254381
add a comment |
add a comment |
B::B(int x):A(x)
{
//Body of B constructor
}
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
add a comment |
B::B(int x):A(x)
{
//Body of B constructor
}
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
add a comment |
B::B(int x):A(x)
{
//Body of B constructor
}
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
B::B(int x):A(x)
{
//Body of B constructor
}
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
answered May 16 '13 at 11:11
SomeWittyUsernameSomeWittyUsername
14.9k22967
14.9k22967
add a comment |
add a comment |
If you are using your derived class constructor just to pass arguments to base class then you can also do it in a shorter way in C++11:
class B : public A
{
using A::A;
};
Note that I have not even used "public" access specifier before it. This is not required since inherited constructors are implicitly declared with same access level as in the base class.
For more details, please refer to section Inheriting constructors at: https://en.cppreference.com/w/cpp/language/using_declaration
Also you may refer to https://softwareengineering.stackexchange.com/a/307648 to understand limitations on constructor inheritance.
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
add a comment |
If you are using your derived class constructor just to pass arguments to base class then you can also do it in a shorter way in C++11:
class B : public A
{
using A::A;
};
Note that I have not even used "public" access specifier before it. This is not required since inherited constructors are implicitly declared with same access level as in the base class.
For more details, please refer to section Inheriting constructors at: https://en.cppreference.com/w/cpp/language/using_declaration
Also you may refer to https://softwareengineering.stackexchange.com/a/307648 to understand limitations on constructor inheritance.
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
add a comment |
If you are using your derived class constructor just to pass arguments to base class then you can also do it in a shorter way in C++11:
class B : public A
{
using A::A;
};
Note that I have not even used "public" access specifier before it. This is not required since inherited constructors are implicitly declared with same access level as in the base class.
For more details, please refer to section Inheriting constructors at: https://en.cppreference.com/w/cpp/language/using_declaration
Also you may refer to https://softwareengineering.stackexchange.com/a/307648 to understand limitations on constructor inheritance.
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
If you are using your derived class constructor just to pass arguments to base class then you can also do it in a shorter way in C++11:
class B : public A
{
using A::A;
};
Note that I have not even used "public" access specifier before it. This is not required since inherited constructors are implicitly declared with same access level as in the base class.
For more details, please refer to section Inheriting constructors at: https://en.cppreference.com/w/cpp/language/using_declaration
Also you may refer to https://softwareengineering.stackexchange.com/a/307648 to understand limitations on constructor inheritance.
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
answered Jul 19 '18 at 15:46
Mandeep SinghMandeep Singh
658
658
add a comment |
add a comment |
class A
{ public:
int aval;
A(int a):aval(a){};
~A();
};
class B : public A
{ public:
int bval;
B(int a,int b):bval(a),A(b){};
~B();
};
int main()
{
B *bobj = new bobj(5,6);
//or
A *aobj=new bobj(5,6);
}
In this case you are assigning the values for base class and derived class .
answered Nov 20 '18 at 11:58
WilsonWilson
112
add a comment |
class A
{ public:
int aval;
A(int a):aval(a){};
~A();
};
class B : public A
{ public:
int bval;
B(int a,int b):bval(a),A(b){};
~B();
};
int main()
{
B *bobj = new bobj(5,6);
//or
A *aobj=new bobj(5,6);
}
In this case you are assigning the values for base class and derived class .
answered Nov 20 '18 at 11:58
WilsonWilson
112
add a comment |
class A
{ public:
int aval;
A(int a):aval(a){};
~A();
};
class B : public A
{ public:
int bval;
B(int a,int b):bval(a),A(b){};
~B();
};
int main()
{
B *bobj = new bobj(5,6);
//or
A *aobj=new bobj(5,6);
}
In this case you are assigning the values for base class and derived class .
answered Nov 20 '18 at 11:58
WilsonWilson
112
class A
{ public:
int aval;
A(int a):aval(a){};
~A();
};
class B : public A
{ public:
int bval;
B(int a,int b):bval(a),A(b){};
~B();
};
int main()
{
B *bobj = new bobj(5,6);
//or
A *aobj=new bobj(5,6);
}
In this case you are assigning the values for base class and derived class .
answered Nov 20 '18 at 11:58
WilsonWilson
112
answered Nov 20 '18 at 11:58
WilsonWilson
112
answered Nov 20 '18 at 11:58
WilsonWilson
112
answered Nov 20 '18 at 11:58
WilsonWilson
112
112
add a comment |
add a comment |
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2
B::B(int val) : A(val) {}
– Andrew
May 16 '13 at 11:11
2
I thought you want to make the destructor take arguments, didn't look like a typo to me. And no need from
!!. Down-vote reverted, remark deleted.– Kiril Kirov
May 16 '13 at 11:21